Twin Lights' elevation made it an ideal spot to conduct other communication activities not associated with the lighthouse. In 1829, the Merchant's Exchange, a commodity exchange for buying and selling goods, erected a semaphore tower here. The tower relayed messages between incoming ships and the Exchange's office in Manhattan, NY. In 1899, Guglielmo Marconi placed an antenna and receiving station at the lighthouse to demonstrate his Wireless Telegraph. His first demonstration was reporting on the America's Cup yacht races occurring off the tip of Sandy Hook. This demonstration worked so well he expanded his operations, making Twin Lights the nation's first wireless telegraph station capable of sending and receiving messages on a regular commercial basis.

The United States Army also saw the value of using Twin Lights as a test site for experimental electronics. In the 1920's and 30's, various radar devices, developed at nearby Ft. Monmouth, were tested here. Many of these prototypes were later used in the early days of World War II.